/Engine/Source/Runtime/Experimental/Chaos/Public/Chaos/PBDRigidClustering.h
GetParentToChildren The parent to children map stores the currently active cluster ids (Particle Indices) as the keys of the map. The value of the map is a pointer to an array constrained rigid bodies.
[FClusterMap](API\Runtime\Chaos\Chaos\FRigidClustering\FClusterMap) & GetChildrenMap()